Ladder lock



Sept. 23, 1958 H. J. TROCHE 2,353,221

LADDER LOCK Filed Dec. 31, 1954 2 Sheets-Sheet 1 NVENTOR. M fi awm/v J rec c/hc ATT ormey Sept. 23, 1958 H. J. TROCHE 2,353,221

LADDER LOCK Filed Dec. 51, 1954 2 SheetsSheet 2 IN V EN TOR.

United States Patent LADDER LOCK Herman I. Troche, Fairview Park, Ohio, assignor to J. H. lblfilan Corporation, Cleveland, Ohio, a corporation of Application December 31, 1954, Serial No. 479,134

2 Claims. (Cl. 228-65) This invention relates to a utility vehicle having an extensible ladder and more particularly relates to an improved latch assembly for preventing uncontrolled extension of the ladder.

The extensible ladder to which this invention is applied usually embodies a base and a fly ladder section mounted on the bed of a utility vehicle for swingable and tiltable movement to provide access to overhead traflic lights, street lamps and similar objects. It is desirable that each of the ladder movements be controlled. For example, uncontrolled extension of the ladder sections is undesirable, particularly when the ladder assembly is located in a horizontal storage position on top the vehicle cab when sudden stopping of the vehicle might result in an extension of the ladder sections.

Accordingly, a principal object of this invention relates to the provision of a releasable latch assembly for preventing uncontrolled extension of an extensible ladder.

Another object of this invention relates to the provision of a latch assembly which automatically conditions the ladder for controlled extension.

Briefly, in accordance with this invention, an extensible ladder having a base section operatively supported on a utility vehicle and carrying an extensible fly section which may be positively extended by a winch mechanism is provided with an improved latch assembly which includes a plunger carried by the fly section and normally biased for latching engagement with a stop member on the base section to prevent extension of the fiy section. The latch assembly also includes an arrangement for automatically disengaging the plunger from the stop member when the winch is operated to extend the ladder and for automatically conditioning the plunger for latching engagement with the stop member when the winch is released for retraction of the extended ladder.

In the drawings;

Fig. 1 is a side view of the utility vehicle illustrating the extensible ladder in its storage position on the vehicle;

Fig. 2 illustrates the ladder assembly and its elevating mechanism in relation to its support on the vehicle;

Fig. 3 is a plan view of portions of the ladder assembly illustrating the ladder extension mechanism;

Figs. 4 and 5 illustrate that portion of the ladder assembly which carries the latch assembly with the latch engaged and disengaged respectively;

Fig. 6 is a view taken along the lines 6--6 in Fig. 4;

Fig. 7 illustrates the plunger portion of the latch assembly in relation to the supporting portion of the fly ladder section;

Fig. 8 is a view taken along the lines 8-8 in Fig. 7; and

Fig. 9 is an exploded view of the latch plunger and its releasing lever.

Referring now more particularly to Figs. 1, 2 and 3 of the drawings, there is shown a utility vehicle 10 having a cab 11 and a ladder supporting bed 12 on which is mounted a vertical stanchion or mast 13 for supporting the extensible ladder assembly. This assembly is made up of the base section 15 and the fly section 16 and, as best shown in Fig. 2 of the drawings, the lower end of the base section 15 is pivotally coupled at 14 to the top of the mast 13 so that the entire ladder assembly may be tilted in a vertical plane relative to the bed and cab of the vehicle. The mast 13 is customarily supported for rotation about a vertical axis on the vehicle bed 12 so that the ladder assembly may be swung to any position in a horizontal plane; the tilting and swinging movement permitting location and direction of the ladder assembly towards overhead traflic lights, street lamps and similar objects.

As best shown in Figs. 2 and 3 of the drawings, the

fly section 16 of the ladder is slideably supported on the base section 15 within suitable guide channels 17 for extension by a suitable winch 18 carried by the base ladder section 15. The extension is accomplished through a winch cable 20 which extends around a free spinning pulley 21 at the upper end of the base section 15 and thence is connected to the fly section 16. Thus, once the ladder assembly is properly located and directed towards an overhead lamp or the like, the winch 18 may be operated to gain access to the lamp. I It will readily be apparent that the ladder section 16 may be extended without operating the winch and that themomentum of swinging and tilting movement might also result in an uncontrolled extension. Similarly, when the ladder assembly is located in the storage position across the cab 11, as shown in Fig. l of the drawings, a sudden stop of the vehicle might also result in an uncontrolled extension of the fly section 16. Accordingly, this invention contemplates the provision of a latch mechanism, the preferred form of which is illustrated in Figs. 4 through 9 of the drawings, which not only prevents uncontrolled extension of the ladder sections but which also is automatically conditioned to release the sections when the winch is operated for extension of the sections.

The latch assembly includes a stop member in the form of a bracket 25 mounted on the top edge of one side rail of the base section 15 and a plunger 27 which is carried within a hollow rung 28 of the fly section 16. The plunger 27 is biased axially by means of a coiled spring 2% into releasable engagement with the stop mem ber 25 as best shown in Figs. 4 and 5 of the drawings. In Figs. 7, 8 and 9 of the drawings, the inner end of the plunger 27 is shown as having a guide slot 30 for receiving the anvil portion 31 of a latch control lever 33. The lever 33 is pivotally supported by a bracket 34 on the hollow ladder rung 28 for controlled intersection with the guide slot 30. The winch cable 20 is threaded through an aperture 36 in the lever 33 so that when a positive extension force is transmitted from the winch 18 as shown by the arrow in Fig. 5 it will turn the lever 33 about its pivot in a direction to position the anvil portion 31 inthe guide slot 30 Where it engages and moves the plunger 27 axially into the ladder rung 28 and out of engagement with the stop member 25, thereby automatically permitting controlled extension of the fly section 16 by the winch. Similarly, release of the winch for retraction of the fly section frees the lever 33 and permits the coiled plunger spring 29 to position the plunger 27 for engagement with the stop member 25, as shown in the dotted lines in Fig. 4. The inner end of the spring 29 engages a rivet 35 fixed in the hollow rung 28.

Thus, operation of the winch automatically operates to release the latch and extend the fly section 16 and also automatically conditions the latch for operation during retraction of the fly section.

The latch arrangement is such that it automatically re- 3 engages upon 'i'etraction ofthe extended ladder section so that the operator is not required to perform any additional operations and yet, the operator is secure in the knowledge that the ladder sections will not inadvertantly extend during the location and direction of the ladder or while the vehicle is transporting the ladder.

I have shown and described what I consider to be the preferred embodiments of my invention along with similar modified forms and suggestions, and it will be obvious to those 'skilled'in the art that other changes and modifications may be made without departing from the scope of this invention as defined by the appended claims.

1. In combination with 'a ladder having a base section and an extensible fly section, each of said ladder sections having ap'air of parallel spaced 'side rails interconnected by a plurality of parallel rungs spaced along the side rails, the dimension between the side rails of the base section being greater than the same dimension of the fly section to permit nesting of the fly section between the siderails of the base section in the retracted position, a bracket secured to the top edge of one of the side rails of the base section, one of the rungs on the fly section being hollow,'a plungerfreely disposed within said hollow rung, resilient means coacting between the hollow rung and the plungerto bias the plunger in an outwardly projecting position beyond the fly section side rail and into the plane of the adjacent base section side rail for interlocking engagement with said bracket to prevent extension of the fly section, and means for retracting the plunger out of engagement with the bracket for controlled extension of the flysection, said last-mentioned means including aligned slots in the plunger and hollow rung and a bell crank 'lever pivotally mounted on the hollow rung with one extremity adapted to be positioned into the aligned 'slots to engage and retract the plunger against the bias into the hollow rung, and a winch having a flexible connection to the other extremity of the bellcrank lever and coacting therewith to position the lever for retraction of the plunger and extension of the ladder fly section.

2. In combination with a ladder having a base section and an extensible fly section, each of said ladder sections having a pair of parallel spaced side rails interconnected by a plurality of parallel rungs spaced along the side rails, the dimension between the side rails of the base section being greater than the same dimension of the fly section to permit nesting of the fly section between the side rails of the base section in the retracted position, a bracket secured to the top edge of one of the 'side rails of the base section, one of the rungs on the fly section being hollow, a plunger freely disposed within said hollow rung,'resilient means coacting between the hollow rung and the plunger to bias the plunger in an outwardly projecting position beyond the fly section'side rail and into the plane of the adjacent base section side rail for interlocking engagement with said bracket to prevent extension of the fly section, and means for retracting the plunger out of engagement with the bracket for controlled extension of the fly section, being a portion of'said bracket being parallel to the plane of its supporting 's'ide rail and transverse to the axis of said plunger, and the remaining portion of said bracket in the direction of extension intersects the plane of its supporting side rail at an angle suflicient to guide the extended plunger along both portions of the bracket for engagement with the rea'rmost edge upon retraction of the ladder fly section.

References Cited in the file of this patent UNITED STATES PATENTS 356,088 Barnes Jan. 18, 1 887 441,159 Herbert Nov. 25, 1890 709,402 Herndon Sept. 16, 1902 857,785 Bobbit June 25, 1907 930,598 Henry Aug. 10, 1909 1,228,248 Rudd May 29, 1917 2,559,992 Painter July 10, 1951 FOREIGN PATENTS 17,594 Great Britain 1'905 

